1. Field of the Invention
This invention relates generally to a process for defining an array of pixels in a thin film electroluminescent edge emitter structure, and more particularly, to a thin film electroluminescent edge emitter structure having an array of discrete light-emitting pixels defined therein via a laser scribing process.
2. Background Information
Thin film electroluminescent edge emitter structures having an array of individually addressable light-emitting pixels defined or formed therein are well known. One such structure is disclosed in U.S. Pat. No. 4,535,341 to Kun et al. which is assigned to the assignee of the present invention. This patent discloses a thin film electroluminescent line array structure which includes a common electrode disposed on a substrate, a first dielectric layer disposed on the common electrode, a second dielectric layer spaced from the first dielectric layer with a phosphor layer interposed therebetween and an excitation electrode disposed on the second dielectric layer. The excitation electrode may be delineated into a plurality of individual electrodes, and the plurality of individual electrodes, in combination with the remaining components of the structure, define the plurality of pixels of the line array. The delineation technique disclosed in Kun et al. for forming the individual electrodes is an ion milling technique, which includes ion milling the excitation electrode material after its deposition on the second dielectric layer. Other known techniques, such as wet or dry etching, may also be utilized to form the plurality of individual electrodes in the excitation electrode with similar results.
Although the ion milling technique disclosed in Kun et al. may be utilized to delineate the excitation electrode at a plurality of locations and thereby form the plurality of individual electrodes, this technique is basically an etching technique which requires the excitation electrode to be appropriately masked with a photomasking material prior to the actual milling phase. The portion of the excitation electrode remaining after ion milling defines the plurality of individual electrodes. It is apparent that placing a masking material on the excitation electrode prior to milling increases the overall number of process steps in the light-emitting pixel forming process and increases the number of pieces of equipment required to form the pixel array. Techniques such as wet etching, although also effective as a means for delineating the excitation electrode, require the use of hazardous chemicals and therefore present obvious safety hazards.
Therefore, there is a need for an improved process for defining an array of individual light-emitting pixels in a thin film electroluminescent edge emitter structure which is relatively simple to implement, time efficient and cost-effective for implementation in a high volume, commercial manufacturing environment.